Exhaust gases containing a silane-based gas or a PFC gas are discharged from a manufacturing process for manufacturing semiconductor devices, liquid crystal panels, solar cells or the like. Such exhaust gases have negative effects on the human body and on the global environment such as a cause of global warming or the like if remain untouched. Therefore, it is not preferable that these exhaust gases are emitted to the atmosphere as they are. Accordingly, these exhaust gases are generally introduced into a combustion-type exhaust gas treatment apparatus where the exhaust gases are made harmless by oxidation through combustion. As a method for treating the exhaust gases, a method in which flames are formed using a fuel gas in a furnace and the exhaust gases are combusted by the flames is widely used.
In such combustion-type exhaust gas treatment apparatus, when the exhaust gases containing silane (SiH4) are treated through combustion (oxidatively treated), silica (SiO2) is produced as expressed by the following reaction formula.SiH4+2O2→SiO2+2H2O
The produced silica (SiO2) is powdery, and adheres to an inner wall of a combustion treatment chamber and becomes increasingly deposited. Therefore, it is necessary to remove periodically solidified powdery material containing silica which has adhered to and has been deposited in the combustion treatment chamber. Thus, a scraper is installed to scrape off the solid matters from the wall surface of the combustion treatment chamber in the exhaust gas treatment apparatus.
The exhaust gas treatment apparatus having this kind of scraper is disclosed in, for example, Japanese Laid-Open Patent Publication No. 2006-275307 and Japanese Laid-Open Patent Publication No. 11-193916.